Air flow filter for use in testing or treatment of the respiratory function of patients



FIG. 1 is a rear perspective view of an air flow filter for use in testing or treatment of the respiratory function of patients, showing my new design;

FIG. 2 is a front perspective view thereof;

FIG. 3 is a side elevation view thereof, the opposite side elevation being identical;

FIG. 4 is a front elevation view thereof;

FIG. 5 is a top plan view thereof, the bottom plan view being identical; and,

FIG. 6 is a rear elevation view thereof. 

The ornamental design for an air flow filter for use in testing or treatment of the respiratory function of patients, as shown and described. 